In the field of chemical hybridizing agents 1-aryl-1,4-dihydro-4-oxo-6-alkylpyridazine-3-carboxylic acids are highly active pyridazine type gametocides. Although these compounds are highly effective as chemical hybridizing agents they do possess the disadvantage of producing plant injury and poor seed quality when overdosed slightly above their effective dosage rate. The 5-carboxypyridazines of the present invention are unexpectedly safer chemical hybridizing agents since they do not have any adverse effects as regards the quality of seed or amount of plant injury at dosage rates far above what is required to produce maximum male sterility which allows for higher percent yields of hybrid seed produced.